code: def test_activation_double_backward(act_name, seed, ctx, func_name):
      from nbla_test_utils import backward_function_tester
  
      act = getattr(F, act_name)
      rng = np.random.RandomState(seed)
      inputs = [rng.randn(2, 3, 4).astype(np.float32) * 2]
  
      backward_function_tester(rng, act, inputs, ctx=ctx)
  
file_path: nnabla/python/test/function/test_binary_activation.py
imports: import pytest
  import numpy
  import nnabla.functions
  from nbla_test_utils import function_tester, list_ctx_and_func_name
label_desc: Use image node_id 6 for calling a global function with example usage: test_activation_double_backward(act_name, seed, ctx, func_name) without return types